Sliding breechblock locking mechanism for self-loading firearms



Abril 22, 1958 B. MAILLARD 2,831,403

SLIDING BREECHBLOCK LOCKING MECHANISM FOR SELF-LOADING FIREARMS Original Filed Marh 30, 1951 2 Sheets-Sheet 1 April 22, 195s B. MAILLARD SLIDING BRE 2,831,403 ECHBLOCK LOCKING MECHANISM FOR SELF-LOADING FIREARMS 1951 2 Sheets-Sheet 2 Original Filed March 30,

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INVENTDR aff/vnu Inf/uffa NEY A it@ SLIDENG BREECHBLCK `LOCKING MECHANISM FR SELF-LOADWG FIREARMS Bernard Maiiiard, Geneva, Switzerland, assigner to Spciety Brevets Aero-Mecaniques, S. A'., Geneva, Switzeriand, a society of Switzerland y `Claims priority, application Luxemburg March 30, 1950 4 Claims. (Cl 89--187) The present invention relates to self-loading firearms (this` term being meant vto include both semi-automatic firearms which require a separate trigger-pull for every shot, and automatic firearms, which lire bursts, and also double action arms capable of working either in semiautomatic or in fully automatic fashion) in which the breech-block structure is held temporarily locked in bore closing or active position by a longitudinal sliding unit carrying the striker and capable, once said breech-block structure has reached said active position, of further moving toward the front to perform this temporary locking action and to lire the cartridge. i

In a different kind of firearm, i. e. repeating firearms, it has been suggested to use'a longitudinally split breechblock, the sections or elements of which, when the breechblock is in its home position, are laterally expanded, into engagement with abutment shoulders provided on the inner walls of the breech-case housing. In suchknown iirearms, the two breech-block elements are pivotally connected to each other about an axis located in the plane of symmetry (normally vertical) of the unit formed by the barrel and the breech-case and the above mentioned abutment shoulders are parallel to this axis. It is very important to give the breech-block elements a longitudinal dimension as small as possible, because said elements support a very great longitudinal thrust every time a shot is tired and they are necesarily slightly oblique. Newy in the known firearms of this type the opening provided in `the breech-case for ejection of the spent cartridgecases is located in one of the sides of said breech-case, that is to'say in one of the walls of the breech-case housing where must be provided one of the above mentioned abutment shoulders. Therefore, since this opening must extend rearwardly behind the rear edge of the cartridge States Patent O ice chamber and since the abutment shoulder is necessarily p breech-case. Thus the abutment shoulders can be located in portions of said breech-case intermediate between the transverse planes passing through the front and rear ends of said openings, and the longitudinal dimension of the breech-block elements is much smaller.

Furthermore, instead of providing pivoting means for interconnecting the front ends of the breech-block elements, these elements are, according to my invention, merely applied against each other along vertical edges, which greatly simplifies the tirearm.

2,831,4@3 l Patented Apr. 22, 1958 Furthermore, the pivot axis about which said two breech-block elements can rotate with respect to each other may be located exactly at the point where the two front edges of these two elements are in contact with each other; thus, when the breech-block elements are locked in their front position, the area of contact with the 'rear face of the cartridge case corresponds to a full circle.

Finally, since the breech-block elements are not directly tixed to each other, they can undergo small individual displacements when they bear against the'correspending abutment shoulder of the breech-case, which ensures an equal distribution of the stresses between the two breech-block elements.

Preferred embodiments of my invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example and in which:

Figs. 1 and 2 show, with some parts removed, respectively in elevation with portions in section on the line I-I of Fig. 2 and in plan view with portions in section on the line II-II of Fig. l, the breech mechanism of an automatic cannon made according to my invention.

Fig. 3 is a plan view, on a smaller scale and partly in section through the horizontal axial plane of the barrel, of the sliding system of this mechanism.

Fig. 4 is a perspective view, with portions cut away, ot said breech mechanism.

Fig. 5 shows a modification of some parts of this mechanism.

The following detailed description relates to the construction of a small bore automatic cannon. v

The firearm includes a barrel 1, preferably removable, extending rearwardly to form a breech case 42.

This barrel and breech case unit has a longitudinal (generally vertical) plane of symmetry. Its walls transverse to said plane, i. e. in the conventional arrangement its top and bottom walls are provided with openings, one of these openings serving to the introduction Vof fresh cartridges and the other to the ejection of spent cartridge cases.

The breech mechanism includes two breech-.block elements 3a and 3b capable of moving transversely between a retracted and unlocked position (shown by Figs. 3 and 5) in which they can reciprocate inside breech case 2, and an active locked position (shown by Figs. 2 and 4) in which they bear upon said breech case, against distinct abutment shoulders 4 made of an especially hard metal,v

the front edges of said breech-block elements then constituting vthe bearing surface which temporarily closes the firearm cartridge chamber behind the rear wall 5a` of the cartridge case 5 in tiring position.

Shoulders 4 are located in a portion of breech case 2 intermediate between the transverse planes passing through the front and rear ends of the two above mentioned openings.

A sliding unit 6 supports both a striker 7 and the above mentioned breech-block elements 3a and 3b, which are slidable on saidunit 6. This unit 6, which is urged frontwardly by return means which will be more exphcitly referred to hereinafter, is adapted to have, once said breech-block elements 3a and 3b have reached the end of their frontward stroke, a supplementary frontward displacement intended first to bring said breechblock elements into locked position and to hold them therein, and finally to re the cartridge.

Breech-block elements 3a and 3b are constituted by two similar pieces mounted symmetrically withv respect to the longitudinal plane of symmetry of the firearm and having front edge lines held adjacent to each other along a vertical line XX', the movements of said elements from their retracted unlocked position to their expanded locked position and vice versa being obtained by horizontal pivoting Ythereof about vertical line XX' (of course 'the terms horizontal and vertical are used onthe assumption that the arm barrel is horizontal and its longitudinal plane of symmetry is vertical).

Sliding unit6 is'arranged to act, -inv the'course'fof its supplementary frontward stroke, as 'awedgefbetween said elements'Sa and 3b sol as to cause'them to pivot about line XXuntil they bear against abutments4.

-The inner Wallsy of breech-block elements 3a and 3b form, opposite block 6, recesses leaving'between said elements a space- C the horizontal section of which decreases gradually toward the front, as clearly shown on Fig. 2- for member 3a and on Fig. 3 for member 3b.

-The' sliding unit is constituted by two bars aguided longitudinally 'in slideways 2a provided for this purpose in the breech case, said slidingbars being interconnected by a cross piece 6b which carriesthe bloclo which forms the active element (with respect to'v elements `*Jaand 3b) of said sliding unit.

Block 6 is provided 'with verticalshoulders- S- inclined outwardly toward the rear and adapted'to bear, `as long as elements 3a and 3b are in retracted position, against surfaces s of corresponding inclination carried' by said elements, the supplementary frontward stroke iof the sliding unit producing, through a cam effect exerted by shoulders S on surfaces s, the outward transverse. pivoting of elements 3a' and-3b which have then reached the end of their frontwardstroke and lhave thus been brought into active position (the position of the respectiveparts rwhen shoulders S start acting on sur'facesfsl is shownfby Fig. 3 and the position of the same parts once locking has' been preformed 'is shown byFig. 2).

The sliding unit carries, on the one hand, near the rear end thereof and preferably on blockcsproper, trigger stops 6c and, on the other hand, near 'the front end thereof andpreferably on cross plate 6b, two-projections 6d (shown on Fig. 4) vwhich determine the limit'frontward position of elements 3a and A3b with respect to unit during the recoil of the reciprocating breechparts and imperatively compel said elements 3a and '3b to move towardeach -other at` the beginning of the recoil 'stroke of the sliding unit. j

I further provide, in the central region of the tfront edges of said elements 3a and 3b, a passage for thepoint of striker 7.

-It shouldbeV noted that I might also, according to a modification illustrated by' Fig, 5, substitute for shoulders S rollers 8 -cooperating with the surfaces s of elements 3a and 3b.

Anyway, the semi-circular 'portions -Ta 'and Tb of the front faces of elements 3a and 3b, which are to constitute the bearing surface for the rear wall a of the cartridge 5 when said elements are in front position; must be located 1in the same -plane when the breech-block'elements occupyttheir locked position, wherebyfsaid cartridge rear Wallis then supported over its whole 'area (position shown for member 3a on Fig. 2). SurfacesTa and Tb will therefore form a dihedral angle when elements'a and 3b are retracted, as shown by Fig. 3.

On the other hand, due to the fact that elements 3a and 3b are still retractedwhe'n they must, byl means of their front edges, pushl a fresh cartridge i'n'to the: cartridge chamber, it is of interest to provide said front edges. labove semi-circular surfacesTa and Tb, with plane surfaces t, and tb the planes of which form, with Vthose of said surfaces Ta and T b,- an angle such that said surfaces ta and tb are located in the sarneplane when-elements 3a and 3b are retracted, and can thus bear through their whole area againstthe rear'wall on the fresh cartridge to be fed (positionshown by Fig. 3,). K

This-firearm -is furtherprovided on the one hand 'with an extractor "9 mounted, `as will be more explicitly 'explainedhereinafter, in cross `piece-fashion lbetween' elementseafand 3b\-'and, on the other l1arid,fwith acontrol device capableofproducingfafter the Efi'ring "of every 4 round, a recoildisplacement of the sliding unit against the action of a recuperator system intended to achieve the frontward return movementv of said sliding unit.

Concerning rst extractor 9, it is arranged in such manner that its nose 9a projects to the front of the front edge of elements 3a and 3b Vand to the inside of the periphery of bearing surfaces Taz-Tb.

Extractor 9 includes a transverse trunnion 9b the journal portions of which engage in housings 10 provided for this purpose inl elements 3a and 3b.

These journals and-housings are arranged in such manner as to make allowance for the pivoting movements of elements 3a and 3b, for which purpose, for instance, and as shown by Fig. 5, vthe journal surfaces of the trunnionarelmade of 'straight cylindrical shape over their whole length andhousings 10 `are given a flaring shape (from their orifice toward their bottom) whereby the journals of the trunnion bear against the front portion of housings 10 when-elements-3a3b are retracted toward each other and against their rear portion when these elements are moved away from each other.

In order to keep said extractor in a position such that it can -grasp the rear part of the cartridge case, I provide two springs 11 housed in longitudinal bores formed for this purposeA respectively yin each of the elements 3a and 3b, said4 springs further tending, due to the fact that their lines of action are oblique with respect to axis XX', to move said elements 3a and 3b away from veach other.

It should benoted that the trunnion also has the function of keeping the two elements 3a and 3b exactly opposite each other, with their vertical edge lines in contact along XX.

Concerning now the device for operating sliding unit 6, it is preferablypfthetype acting by tapping of gas from the firearm barrel.

Although this -control device may be made in the usual manner, that is to say include la driving piston acting upon the sliding unit through a fork and push-pieces housed in the breech case, it seems preferable to arrange said control device according to a particular feature of my invention, applicable to all firearms having a sliding unit intended temporarily to keep the breech mechanism in locked position.

According to this feature, I convey, through a system of conduits 12, the gases tapped from the firearm barrel toward two chambers of variable volume 13, of quadrangular section, provided in the breech case and the movable wall of whichis constituted by the front edge of sliding bars 6a, `said chambers'l `beingconseque'ntly located near the front of the breech case in line with the sliding bars 6a of sliding unit 6.

Concerning the recuperator system which is to return saidl slidingunit frontwardly, it is preferably made, according to another feature of my invention, independent lof the preceding ones, in such manner that it cooperates with the unit in question not directly but through an intermediatepart having a movement simultaneous with that of the sliding unit but of smaller amplitude, whereby it is possible to reduce the overall dimensions of the firearm. v

For this purpose, as'shown by the drawings, I provide each sliding bar 6a with a rack I4 meshing with a pinion 15 carried by a sliding member 16, `preferably of cylindrical shape, movable in 'a longitudinal bore provided for this purpose in the breech case, said pinion 15 rolling on a fixed rack 17 carried by said breech case.

Each sliding member I6, the displacements of which are of an amplitude equal to one half of that of sliding unit 6, cooperates with a return spring 18 housed in the guiding bore of the sliding member.

It should be noted that it will be further of interest to provide, in the usual manner, near the rear of the firearm, an accelerator elastic system (not shown) capable of reinforcing the action of springs 18 by giving sliding unit v 6, when it comes near the end of its rearward stroke, a frontward impulse.

This automatic cannon works as follows:

The sliding unit, which is supposed to start from its extreme rear position (the triggers being depressed) is moved frontwardly by return springs 18, elements 3a and 3b being then located in the retracted position shown by Fig. 3.

In the course of this movement, the surfaces ta and tb of the front edges of said elements (which surfaces are then located in the same plane) push against the rear part of the cartridge to be fed and introduce said cartridge into the cartridge chamber at the end of their frontward stroke.

Once elements 3a and 3b have reached their limit frontward positions, sliding unit 6 starts on its supplementary frontward displacement, shoulders 5 pushing said elements 3a and 3b into locked position (as shown by Fig. 2) and finally, striker 7 strikes the rear part 5a of the cartridge already housed in the cartridge chamber, thus tiring the shot. During the whole of the supplementary stroke of sliding unit 6, subsequent to the bringing of elements 3a and 3b into active position, said unit opposes any unlocking of said elements.

The gases tapped from the arm barrel then act directly upon the front edges of sliding bars 6a and cause the sliding unit to recoil and, when it has moved rearwardly a suicient distance, this unit ceases to hold elements 3a and 3b. Due to the fact that the slope angle of abutment Y4 is reversible, the thrust exerted by the cartridge case, in combination with the action of projections 6d, compels elements 3a and 3b to retract toward each other and. then to slide rearwardly `together with the sliding unit. In the course of this recoil movement, the extractor catches the spent cartridge case which is expelled through the action of a mechanism not shown by the drawing. When the recoil movement is nished and supposing that the triggers have not been released, the whole of the sliding unit 6 and elements 3a and 3b starts back in the frontward direction under the combined actions of the accelerator system and return springs 16. The same cycle of operations is then repeated.

The chief advantages of my system are its simplicity, its light weight and its performance, especially concerning the rate of lire.

These advantages result in particular, as already above explained, from the fact that the conventional heavy breech-block is replaced by light elements which are locked directly on the breech case, from the small length of these elements and from the direct pneumatic control of the sliding unit.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and ecient embodiments of my invention, it should be well understood that I do not Wish to be limited thereto as there mightbe changes made in the arrangement, disposition and form of the parts Without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

The present application is a division of my U. S. application Ser. No. 218,370, filed March 30, 1951, now Patent No. 2,756,640. t

What I claim is:

1. A self-loading ream which comprises, in combination, a barrel including a cartridge chamber, a breech case at the rear of said barrel, said barrel and said breech case having a longitudinal plane of symmetry, said breech case being provided, in the two walls thereof perpendicular to said plane of symmetry, with two openings respectively, one for introduction of fresh cartridges and the other for ejection of spent cartridge cases, a sliding unit including two longitudinal side bars longitudinally guided in said breech-case between said openings and a cross plate extending between said bars, said sliding unit being reciprocable longitudinally in said breech case with a. given stroke, two breech-block elements symmetrical with respect to said longitudinal plane of symmetry and longitudinally guided with a limited relative displacement with respect to said unit, said relative displacement being smaller than said stroke whereby said breech-block elements are reciprocable longitudinally with respect to said breech case, two locking abutments carried by the inner walls of said breech case located on opposite sides of said plane of symmetry, said abutments being located in a transverse plane located between the front and rear ends of said openings, the rear edges of said breech-block elements being shaped to cooperate with said locking abutments respectively to be locked in Acartridge chamber closing or active position, said two breach-block elements adjoining each .other at fthe front along a line at right angles to the axis of said barrel and located in saidlongitudinal plane of symmetry and being pivotable with respect to said sliding unit in opposite directions about said line, so as to be able, at the end of their frontward stroke, to have their rear edges engaged with said locking abutments, a block rigid with said cross plate including shoulders arranged to engage in wedge-like fashion between said breech-block elements for pivoting them outwardly into ,cooperating engagement with said locking abutments and to hold them thus engaged during the supplementary frontward displacement of said sliding unit made possible by its limitedlongitudinal sliding relation with said breech-block elements, means operative by the ring of each round for imparting a rearward impulse t0 said sliding unit and elastic means for urging said sliding unit frontwardly after each rearward stroke thereof.

2. A firearm according to claim 1 in which said sliding unit carries, near the front end thereof and on its cross plate, two projections arranged to determine the limit frontward position of the breech-block elements with respect to the sliding unit and imperatively to compel them to move toward each other at the beginning of the recoil stroke of the sliding unit.

3. A firearm according to claim 1 including Semi-circular surfaces on the front edges of said breech-block elements to bear against the rear wall of a cartridge in the cartridge chamber when said elements are in active position, said semi-circular surfaces being located in the same plane when these elements are in locked position.

4. A rearm according to claim 1 including semi-circular surfaces on the front edges of said breech-block elements to bear against the rear wall of a cartridge in the cartridge chamber when .said elements are in active position, said semi-circular surfaces being located in the same plane when these elements are in locked position, the front edges of said breech-block elements being further provided, above said semi-circular surfaces, with dat surfaces oblique with respect to said semi-circular surfaces so as to be located in the same plane when the breech-block elements are retracted.

References Cited in the tile of this patent UNITED STATES PATENTS 2,590,981 Lippert Apr. 1, 1952 FOREIGN PATENTS 62,484 Denmark July 3, 1944 897,374 France Dec. 4, 1944 574,352 Great Britain Jan. 2, 1946 

